Effect of thickness and working temperature on sensitivity of TiO₂ thin film

TiO₂ sensing films were prepared by dip-coating TiO₂ sol on Al₂O₃ substrate. Effect of thickness and working temperature on the sensitivity of TiO₂ thin films was studied. The result indicated that the sensitivity of the films changed as the film thickness and working temperature varied, and there existed an optimal thickness and an optimal working temperature. XPS result indicated that the adsorbed oxygen would decrease when films were tested in hydrogen-containing environment. The sensitive mechanism of TiO₂ films to the hydrogen was discussed. The reason for existing an optimal thickness and work temperature could be explained by reaction between adsorbed oxygen and hydrogen and absorption and desorption theory. Sensitivity of TiO₂ films was also related to the electron transfer from the film surface to the electrodes.